Taking a view on aircraft hangar smoke detection
Published on 27 February 2009
In this article, Ian Moore, Managing Director of D-Tec (Detector Technologies Limited) explains the issues involved in protecting against fire hazards in aircraft hangars
There is little doubt that aircraft hangars, due to their sheer size and volume, represent an especially testing environment when it comes to fire safety.
More specifically, the potential to actually detect smoke before a large-scale fire has taken hold may be problematic using conventional methods, due the way smoke and fire behaves, especially the influence of factors such as stratification and temperature layering. The effects of a blaze can be quite literally devastating, both in terms of the irretrievable damage to the hangar's structure, equipment and any aircraft it contains, and the associated injuries - or worse - for workers inside and the firefighters tackling a blaze.
This potential for large-scale disruption was amply demonstrated by a fire in a maintenance hangar at Brussels International Airport in May 2006 where, despite the best efforts of more than 100 firefighters, the hangar - which at the time contained four large aircraft - completely collapsed. The severity of the fire was such that it was only 36 hours later that the blaze was completely extinguished.
So what can be done to address this problem? When it comes to providing an early warning of fire in aircraft hangars there is one type of technology, based on the intelligent analysis of CCTV images, which is being increasingly deployed to protect these valuable assets. This CCTV-based solution is aptly referred to as Video
Smoke Detection (VSD) - a technology pioneered by D-Tec - and is a capability that is now operational in a wide range of commercial and military aviation sites across the globe.
To give an idea of the extensive user base, current applications for VSD include: Virgin Blue's hangar at Brisbane Airport, Australia; in the Middle East at an Oman Airforce hangar and also at the Royal Airwing Hangar in Dubai - the world's largest privately owned aircraft hangar, and, closer to home, the British Airway's hangar at Heathrow Airport, London, which formerly housed its iconic Concorde fleet.
The benefits of VSD
The beauty of Video Smoke Detection (VSD) is that it takes detection to the fire rather than waiting for the fire to come to the detector. This approach is ideally suited to the large voluminous nature of aircraft hangars where high airflows are present and it is just not possible, practically, to place conventional detectors close enough to the area of risk to provide an effective level of detection.
In lofty, extensive, structures such as aircraft hangars there is a high reliance, where traditional fire detection solutions are concerned, in smoke overcoming distance, stratification and temperature layering, before being detected. This can mean, with conventional detectors, that it can be many minutes before an alarm is activated - if at all - making it much more problematic to tackle a blaze as it is likely to have reached a more advanced stage.
Thankfully, this is not a limitation faced by Video Smoke Detection (VSD) as it is able to utilise images from standard CCTV cameras and analyse these, by applying sophisticated algorithms to detect the presence of smoke
in seconds and automatically alert control room operators to the danger. Consequently VSD is not reliant on the proximity of smoke to a detector, whether the camera is 10 or 100 metres away from a risk area, VSD will detect smoke in the same amount of time.
Although it is claimed other camera-based systems are able to detect smoke, the reality is that these are really motion detectors or obscuration-change detectors which are unable to differentiate between smoke and other sources of movement and so are prone to false alarms.
In terms of practicality, the CCTV cameras associated with VSD can be fixed in conveniently accessible places, rather than being positioned well out of reach, as is the case with conventional detectors. Additionally CCTV can cover a much larger area so less cameras would normally be required compared to detectors for a given size of hangar. It may also be possible to take advantage of already installed, security, CCTV cameras for some of the monitoring.
Protecting the world's largest privately-owned aircraft hangar
When it comes to aircraft hangars, one of the standout installations of Video Smoke Detection (of the more than 20 we have been involved in worldwide) in terms of its sheer scale has to be the world's largest privately-owned aircraft hangar, the massive Royal Airwing Hangar complex at the Dubai International Airport in the UAE.
Home to the Dubai ruling family's private aircraft, the huge open-span, eight-bay Royal Airwing Hangar is 600 metres wide and 110 metres deep, and holds up to eight aircraft with a total value that industry experts say could well exceed £2 billion. This includes the 79.8 metre wingspan Airbus A380. At the front, the hangar has eight sets of doors that span 584 metres, each of which is 25.8 metres high.
Initially, linear heat cables in the open roof void were specified as the primary means of fire detection. However, consultants and fire officers responsible for the building were concerned that serious damage to the parked
aircraft would have already resulted by the time either the smoke or heat reached the detectors. Aspirating smoke detection systems that draw sampled air into the detector are similarly challenged in high ceiling height structures as, again, smoke still has to reach the sampling position in the roof before the alarm is activated.
Another consideration that encouraged the hangar's consultants and fire officers to seek a faster more reliable solution was the fact that the hangar's huge doors would be open most of the time. This means that there would be no reliably predictable airflow route, leading them to the conclusion that the only dependable solution was to seek an 'at source' detection system. A visit to the D-Tec protected British Airway's hangar at Heathrow Airport in London persuaded them that the best solution was D-Tec's FM-approved VSD system.
The final solution for the Royal Airwing Hangar complex comprised a combination of infrared flame detection and D-Tec's VSD system. The flame detectors are fitted below wing height, while the VSD CCTV cameras are installed around the perimeter of the hangar, 15 metres above floor level, just above the planes' wing height. This ensures that the VSD system will detect smoke escaping from any aircraft doors or appearing above wing level from a fire lower down. The systems are linked together so that, should one or both detect smoke or flame, the alarm is automatically triggered and the hangar's Tyco Suppression Systems' foam extinguishing system is activated.
Eight CCTV cameras are used to protect each of the eight areas of the hangar, resulting in a total of 64 cameras.
Each eight-camera area is individually wired to one VSD unit, and four areas - or 32 cameras - are connected to one of two rack-mounted systems. Each camera has a 40-degree field-of-view and is located no further than 60 metres from the furthest detection point. The two VSD rack-mounted units are located in a central manned control room, and each rack consists of an integral monitor, keyboard and mouse.
The installation for the Royal Airwing Hangar was devised by D-Tec's engineers in the UK working closely with colleagues from BSS-ME in Dubai, D-Tec's distributor in the Middle East. The VSD equipment was supplied to Honeywell and the installation was carried out by BK Gulf's BCL Fire Systems division, part of the Dutco Balfour Beatty Group.
The future of VSD
Looking ahead, these are exciting times for Video Smoke Detection. VSD's capabilities have been further enhanced by the potential for images and alarms to be distributed, for review, over the network to a number of viewing platforms. This is being realised through solutions such as our own FireVu system which readily integrate the well-recognised advantages of VSD with IP (Internet Protocol) based functionality. In practical terms, this advance means that, for ease of management, it is perfectly possible for a number of geographically dispersed aircraft hangars to be monitored from the same control room and more to be added should the need arise. There is also the ability, with this flexible approach, for changes to configuration, testing and diagnosis to be carried out remotely - removing cost and delay.
Ian Moore, Managing Director - D-Tec (Detector Technologies Limited)
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